Received Date: 28 September 2018; Accepted Date:29 september2018; Published Date: 11 October 2018

Background:Interventional oncology (IO) using Yttrium-90 (Y-90) TheraSphere and SIR-Spheres has become an integral part of the treatment strategy for unresectable hepatocellular carcinoma (HCC) and hepatic metastases. SIR-Spheres, which consist of Y-90 resin particles, are FDA approved for treatment of liver metastases, though they are well known for their use for treating unresectable HCC [4]. TheraSphere consists of Y-90 glass microspheres and is FDA approved for treatment of HCC [2].

Y-90 is a beta emitter with a decay product of Strontium-90 (Side note: SIR-Sphere resin is a pure beta emitter whereas TheraSphere glass particles have impurities). Y-90 has a decay energy of 2.28 MeV and a half-life of 64.1 hours [3]. As beta radiation, greater than 90% of its energy is deposited in the first 5mm of tissue making it ideal for locoregional treatment strategies. However, its high radiation levels require careful technique and monitoring during treatment to ensure safety of the patient and involved personnel. [1]

Before “the Event” at our institution, standard practice for TheraSphere preparation was to have the interventional radiology (IR) technologist prepare the TheraSphere administration accessory kit prior to patient arrival in the fluoroscopy suite. This included connecting and priming all required tubing for delivery, preparing the acrylic box containing the lead pot and dose vial, connecting and turning on the electronic dosimeter, and spiking the vial with the needle injector assembly. The needle injector assembly makes an audible click when pressed and locked into position with the vial, ensuring an adequate seal. The force needed to lock the assembly in place can be substantial requiring careful technique. The injector assembly has two side arms which are pressed down to spike the vial, creating a second audible click once fully engaged. The acrylic box and all instruments required for TheraSphere delivery were placed on a sterile cart prior to assembly, and a floor drape was placed under the cart. Radiation safety staff were present for the case to check the patient and equipment after the procedure to ensure proper deployment of the Y-90, though personnel were allowed to enter and exit room without being checked with a Geiger counter each time.

The Event:

A technologist at our institution prepared the TheraSphere administration accessory kit per usual protocol; however, a misstep caused an unintentional and unrealized leak of Y-90. The technologist responsible for the incident had connected all tubing and spiked the vial with the needle assembly as usual, though an audible click was not clearly heard when securing the injector assembly to the vial. With the lid removed, the technologist began priming the tubing. During this process, fluid leaked unknowingly from the box onto the technologist and the floor. At the time of the incident, the technologist noticed air in the line and was concerned that the tubing had not been properly flushed before spiking the vial, the tubing was not connected correctly, or the vial was not completely spiked. The technologist then left the room and traveled to the IR reading room wearing boot covers to inform the interventional radiology staff physicians on service, unaware of being contaminated. The incident was ultimately confirmed to be a Y-90 TheraSphere leak from the dose vial onto the floor and technologist, and was subsequently spread locally throughout the IR department and into the reading room.

Immediate Response:

The Public Safety Response Team (PSRT), an organization available for emergent quality control, was called immediately following the incident. The IR department and reading room were thoroughly scanned with radiation detection equipment confirming the spill of Y-90, which had spread from the fluoroscopy room to the reading room. The technologist’s surgical boot covers were removed and disposed of in a radiation safety container, the technologist was emergently quarantined, clothing was removed, and entire body was washed to remove all possible contamination. The cleanup of the spill was extensive, with the entire IR department shut down for one day and the fluoroscopy room containing the spill shut down for approximately two weeks. Several areas of contaminated carpet in the IR reading room were even replaced to ensure safe levels of radiation prior to returning to work.

Long term practice changes/Discussion:

Immediately following this hazardous event, department wide changes were implemented to reduce the chance of another similar occurrence. The technologists’ responsibilities remain to prepare the acrylic box containing the lead pot and dose vial prior to the patient’s entering the room. However, the lead pot lid remains attached and a physician is required to remove the lid and spike the vial with the needle injector. The department now requires a radiation safety officer to be present during box preparation, throughout Y-90 delivery (both SIR-spheres and TheraSphere), and until the radiation jar is sealed from cleanup. Strict management of personnel entering and leaving the room has also been implemented for all Y-90 treatments. This includes thorough scanning of hands and feet upon leaving the room with a Geiger counter, monitored by a radiation safety officer. All personnel must also wear a double layer of shoe protection. A brief scan of the patient, delivery catheters and tubing, and surrounding area is performed with a Geiger counter by a radiation safety officer following each Y-90 treatment. Following the implementation of these changes approximately one year ago, there have been no reported radiation spills to date.

Conclusion:

As Y-90 practice grows and gains popularity, safety and ALARA is important now more than ever. As demonstrated at our institution, accidents can happen even after a decade of high-volume Y-90 administration. One mistake in the preparation process for Y-90 delivery can lead to a devastating event, risking patient and employee safety, and limiting departmental resources due to the extensive cleanup and downtime required. Learning from our mistakes and implementing departmental changes has overall created a safer workplace with more thorough protocols in place that will better keep everyone safe and the department running smoothly.